Electrical signal generating apparatus

ABSTRACT

Electrical symbols representative of alphanumeric characters are generated by impressing the characters in a line on a record medium carried on a platen and producing relative movement between the platen and a scanning device so that the line of characters is scanned by a plurality of electrooptical devices yielding the signals.

Bas 197 1 Inventor Hassan Paddy Abdel Salam [56] References Cited ra; England UNITED STATES PATENTS 72 Qf 2 1969 2,551.726 5 1951 c661e 340 1463 x I 2,616,983 11/1952 Zworykin et al..... 340/1463 X [451 2 889 535 6/1959 Rochester etal 340/146 3 [731 Assigme Unims" 3 55 357 6/1966 K 1 1 178/6 LCR X Durban Soum AH apanye a. (32] Priority Apr. 24, 1968 Primary Examiner-William C. Cooper [33] Great Britain Assistant Examiner-William A. Helvestine [31 1 19404/68 Ar!0rneyLawrence E. Laubscher [54] ELECTRICAL SIGNAL GENERATING APPARATUS 9 Claims, 4 Drawing Figs.

[52] U.S.Cl 1. 178/81, ABSTRACT: Electrical symbols representative of alphanu- 340/146.3 F meric characters are generated by impressing the characters [51] Int. Cl 606k 9/00, in a line on a record medium carried on a platen and produc- H04! 17/ 14 ing relative movement between the platen and a scanning [50] Field of Search 178/6, 7.2, device so that the line of characters is scanned by a plurality of 340/ 1 46.3 electrooptical devices yielding the signals.

F 2 E2 78 20 I 22 If I 4st, 2/ 1 i 42 PATENTED JUL 6 BEST AVAILABLE COPB; 59 1, 7 21 INVENTOR ATTORNEY ELECTRICAL SIGNAL GENERATING APPARATUS The present invention relates to means for developing electric signals representative of alphanumeric characters; such signals are required, for example, for the operation of information display apparatus of the kind described in my US. Pat. application Ser. No. 762,195 filed on Sept. I6, 1968.

The invention provides a simple means of producing electrical signals relating to the scanning of alphanumeric characters.

It is an object of the present invention to provide electrical signal generating means in which use is made of conventional typewriter means to provide characters from which signals are generated.

It is a further object of the invention to make use of the relative movement between the type members and platen of a typewriter means to provide a scanning movement for character signal generation.

Another object of the invention is to provide a modification to a conventional typewriter means whereby improved operation for character generation is obtained.

Features and advantages of the invention will become apparent from the following description of an embodiment thereof, taken in conjunction with the drawing, comprising FIGS. 1 to 4, ofwhich:

FIG. I is a diagram illustrating the method by which electrical signals are derived by signal developing means in accordance with the invention;

FIG. 2 is a schematic front view of a typewriter modified for the purposes of the present invention;

FIG. 3 is a partly sectional schematic side view of the modified typewriter shown in FIG. 2; and

FIG. 4 is a diagram illustrating an alternative mode of construction of a part of the apparatus described in relation to FIGS. 2 and 3.

FIG. 1 shows how an alphanumeric character 1 (shown for convenience as being the letterA) imprinted upon a paper sheet 2 may be scanned by producing relative movement between the paper and a linear array 3 of electrically photosensitive devices 4, each traversing a respective path across the character. The electric signals thus derived from photocells 4 may be used in conjunction with display apparatus as described in US. Pat. application No. 762,195 mentioned above to produce a display of the alphanumeric character scanned.

A convenient way of constructing an apparatus in accordance with the invention is to modify a normal typewriter, the platen and platen transport means then being provided by the platen and carriage of the typewriter and the impression means being provided by the type bars or type head of the typewriter, The record member may then be constituted by a sheet of paper fed around the platen in the normal manner, though other substances, such as reflective plastics film, may be used if found advantageous.

FIGS. 2 and 3 show how, in accordance with the invention, a conventional typewriter may be modified to provide an apparatus in accordance with the invention for generating electrical signals.

To a suitable point on the frame of typewriter 11 is secured a bracket 12 on which is mounted a scanning device 13 directed to that line of a sheet of paper 19 carried upon the platen 14 on which characters are typed by pressing the typewriter keys, as indicated by the characters AB shown at 15 behind the cutaway typewriter ribbon 30. As shown in FIG. 3, scanner 13 may include a lens 16 which images a vertical portion of the typed line of characters upon a surface containing a linear array 17 of electrically light-responsive devices, conveniently solid-state devices such as photodiodes or phototransistors. The portion of the platen upon which scanning is effected is preferably illuminated by a lamp 18, which is also secured to the typewriter frame. In the usual manner the typewriter platen is carried upon a spring-biased carriage 22, the carriage being allowed to move by an escapement mechanism in response to actuation of any character key or released for continuous movement in response to the spring bias by actuation of a tabulator control.

After a message line has been typed the carriage is restored to its right-hand limiting position and the escapement is released by pressing the conventional tabulator key. In the majority of typewriters, leftward movement of the carriage after the tabulator key has been depressed is controlled only by a simple pad brake actuated by the tabulator key. For the purposes of the present invention this simple control does not always provide a sufficiently slow or sufficiently constant carriage movement. Therefore a further modification to the typewriter may comprise a known centrifugal friction governor 20 coupled by way of a pinion 21 with a rack 22 moving with carriage. This device is arranged to be brought into action to control the speed of traversal of the carriage only when the tabulator key 42 is actuated to initiate a scanning operation, To this end tabulator key 42 is coupled by way of a lever 43 to a frame 44 which is pivoted at 45 to the typewriter frame 46. In the position shown in the drawing key 42 has been depressed to release the ratchet and pinion 21 has been raised into engagement with rack 22. When key 42 is released, frame 44 will pivot in a clockwise direction about pivot 45 to release pinion 21 from engagement with rack 22.

An alternative scanning device, of which the principle is illustrated by FIG. 4, traverses along the typed line of characters a linear array 32 formed by the ends of a plurality of lightguides such as 33. Each of these light-guides thus receives light from a respective restricted area of the paper 34. The end of the light-guide next to the paper is bevelled to allow light directed in the general direction of arrow 25 from a point in front of the paper at which point a light source is preferably placed, to pass after reflection from the paper into the lightguide, along which it is transmitted to an individual electrically light-sensitive device 36, preferably a solid-state device such as a photodiode or phototransistor. In this case the lightguides can be accommodated beneath the typewriter or elsewhere to avoid obstructing the working area of the typewriter. For a normal typewriter with a character height of 0.] inch the light-guides may have a diameter of 0.005 inch and may be spaced at a center-to-center spacing of 0.008 inch.

This last-described embodiment of scanning device is particularly suitable for use on a typewriter of the moving typeglobe type, in which case the scanner is arranged for movement with the moving typeglobe. It is, of course, necessary to provide a modified and constant-speed movement of the typer and scanner assembly, by means similar to the governor described for the moving-carriage typewriter. It is not considered necessary to illustrate this modification.

Iclaim: I

I. An electrical signal generating apparatus comprising in operative combination:

a cylindrical platen rotatable about in axis;

a record medium on said platen;

impression means operable to impress press a line of symbols upon said record medium, said line extending parallel to said axis;

scanning means mounted adjacent to said platen and arranged in a linear array extending perpendicular to said axis, said scanning means including a plurality of electrically light-sensitive devices and operative to cause light from each of a plurality of portions of said record medium to pass simultaneously to respective ones of said electrically light-sensitive devices;

and transport means operable to produce rectilinear relative movement between said platen and said scanning means in the direction of said line of symbols whereby, in response to said relative motion of said platen and scanning means, each of said light-sensitive devices yields electrical signals representative of the scanning of said line of impressed signals along an individual scanning line.

BEST AVAILABLE COPY 2. The invention claimed in claim 1, characterized in that said impression means includes a plurality of type bars each operable by an individual key to make a respective impression on said record medium.

3. The invention claimed in claim 1, characterized in that movement control means are provided for producing said relative movement of said platen and said scanning means at a substantially constant speed.

4. The invention claimed in claim 3, characterized in that said transport means includes a rack movable therewith;

said movement control means including:

pinion means engageable with said rack;

frame means mounting said pinion means and operative to move said pinion means into and away from engagement with said rack;

and governor means mounted on said frame means, said governor means being connected to said pinion means and operative to control the speed of movement of said transport means when said pinion means is engaged with said rack.

5. The invention claimed in claim 4 characterized in that said governor means is formed by a centrifugal friction governor.

6. The invention claimed in claim 4 wherein said frame means is mounted for pivoted movement relative to said rack;

said transport means includes:

carriage means supporting said platen for movement relative to said scanning means;

and depressible actuator means operative when depressed to initiate movement of said carriage means;

and said movement control means includes:

linkage means connected between said frame means and said depressible actuator means, said linkage means operating upon depression of said depressible actuator means to pivot said frame means and move said pinion means into engagement with said rack.

7. The invention as claimed in claim 1, characterized in that said scanning means is fixed relative to said platen and includes lens means operative to provide an optical image of said portions of said record medium on said light-sensitive devices.

8. The invention claimed in claim 1, characterized by a fixed light source disposed to illuminate said portions of said record medium.

9. The invention claimed in claim 1, characterized in that said scanning means includes a plurality of light-guides, each of said light guides conducting light from respective one of i said record medium portions to an individual one of said lightsensitive devices. 

1. An electrical signal generating apparatus comprising in operative combination: a cylindrical platen rotatable about in axis; a record medium on said platen; impression means operable to impress Press a line of symbols upon said record medium, said line extending parallel to said axis; scanning means mounted adjacent to said platen and arranged in a linear array extending perpendicular to said axis, said scanning means including a plurality of electrically lightsensitive devices and operative to cause light from each of a plurality of portions of said record medium to pass simultaneously to respective ones of said electrically lightsensitive devices; and transport means operable to produce rectilinear relative movement between said platen and said scanning means in the direction of said line of symbols whereby, in response to said relative motion of said platen and scanning means, each of said light-sensitive devices yields electrical signals representative of the scanning of said line of impressed signals along an individual scanning line.
 2. The invention claimed in claim 1, characterized in that said impression means includes a plurality of type bars each operable by an individual key to make a respective impression on said record medium.
 3. The invention claimed in claim 1, characterized in that movement control means are provided for producing said relative movement of said platen and said scanning means at a substantially constant speed.
 4. The invention claimed in claim 3, characterized in that said transport means includes a rack movable therewith; said movement control means including: pinion means engageable with said rack; frame means mounting said pinion means and operative to move said pinion means into and away from engagement with said rack; and governor means mounted on said frame means, said governor means being connected to said pinion means and operative to control the speed of movement of said transport means when said pinion means is engaged with said rack.
 5. The invention claimed in claim 4 characterized in that said governor means is formed by a centrifugal friction governor.
 6. The invention claimed in claim 4 wherein said frame means is mounted for pivoted movement relative to said rack; said transport means includes: carriage means supporting said platen for movement relative to said scanning means; and depressible actuator means operative when depressed to initiate movement of said carriage means; and said movement control means includes: linkage means connected between said frame means and said depressible actuator means, said linkage means operating upon depression of said depressible actuator means to pivot said frame means and move said pinion means into engagement with said rack.
 7. The invention as claimed in claim 1, characterized in that said scanning means is fixed relative to said platen and includes lens means operative to provide an optical image of said portions of said record medium on said light-sensitive devices.
 8. The invention claimed in claim 1, characterized by a fixed light source disposed to illuminate said portions of said record medium.
 9. The invention claimed in claim 1, characterized in that said scanning means includes a plurality of light-guides, each of said light guides conducting light from respective one of said record medium portions to an individual one of said light-sensitive devices. 